I heard an interesting idea for a hypothetical theocracy DLC that fielded the argument that the dynastic gameplay only needs to be metaphorical, and the natural equivalent of a dynasty within the Catholic Church is a monastic order. So the unit of gameplay should be chapters and orders of the Templars, Hospitallers, Teutonics, Livonians, Franciscans, Benedictines, etc, with Monasteries as their local branches analogous to republican trading posts, which in those days were huge centers of proto-capitalist economic activity too. Even the non-militarized monastic orders have a massive amount of capital they control. They really are just republics on land.
The idea went on to spell out that the direct equivalent to political marriage was nepotistic induction of novices from wealthy families. A professor I had compared it all to the college admissions scandal and how anybody can get into a college but rich people compete to get their kid into a GOOD college, likewise nobility had a sense of what was a prestigious monastery or monastic order and did jockey to get their children into the good ones.